Patent DE-102008056695-A1 (DE)
Title: Laser processing head for processing of workpieces by laser radiation, comprises a housing through which an optical path is guided to the laser beam and which has a focusing optic for focusing the laser beam on the workpiece
Inventor: SCHUERMANN BERT
IPC: B23K26/04
Filed: 2008-11-11
Abstract: The laser processing head comprises a housing (14) through which an optical path is guided for laser beam (12) and which has a focusing optic (18) for focusing the laser beam on workpiece (16) to be processed within a processing area, an illumination device (36) with a first light source for uniform illumination of the processing area of the workpiece to be processed, and a light interference device with a second light source, which is suited to a light fan to throw in direction of the workpiece to be processed in order to produce a light line within the processing area on the workpiece. The laser processing head comprises a housing (14) through which an optical path is guided for laser beam (12) and which has a focusing optic (18) for focusing the laser beam on workpiece (16) to be processed within a processing area, an illumination device (36) with a first light source for uniform illumination of the processing area of the workpiece to be processed, a light interference device with a second light source, which is suited to a light fan to throw in direction of the workpiece to be processed in order to produce a light line within the processing area on the workpiece to be processed, and a charge-coupled-device camera for the observation of the processing area of the workpiece to be processed. An optical band-pass filter is arranged before the camera in an observation beam path. The first and the second light sources are obtained so that they have a local radiation maximum in the wavelength passage region of the band-pass filter. The band-pass filter is a Fabry-Perot filter. The band-pass filter comprises a wavelength passage region, whose half-width is smaller than 20 nm. The light interference device is arranged firmly to the focusing optic so that the light fan of the second light source arrives diagonally to optical axis of the laser beam on the workpiece to be processed so that a distance between the focusing optic and the workpiece is determined by triangulation. The light fan of the second light source lies in a plain that passes diagonally to the optical axis of the laser beam and which includes the focus of the focusing optic on the workpiece turning point side. The second light source is a semiconductor laser and the first light source of the illumination device is a xenon flash bulb or a mercury vapor lamp. The first light source of the illumination device is resonant cavity LED and comprises a laser and a temporally varying diffuser at its beam exit side. The laser beam is produced by the laser passed through the diffuser in order to dissolve the coherence of the laser light. The first light source of the illumination device comprises lasers, whose laser light is superimposed so that the resulting illumination of the illumination device yields incoherent light. The observation beam path of the camera is coupled coaxially in the laser beam path through a first beam splitter. A second beam splitter is arranged in the observation beam path between first beam splitter and the camera through which the illumination of the illumination device is coupled coaxially to the laser beam path. The first light source for the illumination of the workpiece and the second light source for producing the light fan are arranged together in a light interference-illumination device arranged on the housing.